This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are trying to measure the ER Ca2+ concentration via a FRET based cameleon Ca2+ sensor and test drug effect and outcome from gene-silencing. In general, cells expressing this yellow cameleon protein need to be excited at 420 nm and dual emission pictures will be collected by rapidly alternating D485/40 and D535/30 emission filters. Then, background-corrected emission intensities at 535 nm and 485 nm will be averaged across individual cells to yield a raw F535/F485 emission ratio, which will decrease when the ER Ca2+ concentration gets lower.